JPH07329595A - Differential limiting control device - Google Patents

Abstract

PURPOSE:To heighten the traveling stability of a vehicle by controlling differential limiting torque so that the vehicle obtains a desired yaw rate, using an active control type differential limiting device. CONSTITUTION:A vehicle provided with an active control type differential limiting device (a) is provided with a means (b) for detecting the vehicle speed, a means (c) for detecting the steering angle of the vehicle, a means (d) for computing an actual yaw rate on the basis of the detection signals of the means (b), (c), a means (e) for computing a target yaw rate, and a means (f) for controlling differential limiting torque on the basis of the computed value so as to make the actual yaw rate coincide with the target yaw rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle differential limiting control device having an active control type differential limiting device.

[0002]

2. Description of the Related Art As a differential limiting device (referred to as LSD) for preventing one wheel from slipping and slipping on a slippery road surface or muddy, a torque sensitive type that produces a differential limiting torque proportional to an input torque. In addition to the rotation difference sensitive type that generates a differential limiting torque according to the rotational difference between the left and right wheels, an active control type that can arbitrarily adjust the differential limiting torque from the outside is known (see “Tochigi Fuji Sangyo Giho”). Vol.3 No.
1 ”).

[0003]

By the way, in the case of a vehicle equipped with an ordinary differential, the yaw rate overshoot is likely to occur due to the moment of inertia during steering operation as shown by the solid line in FIG. There is a tendency to become unstable. Also, when equipped with a torque-sensitive or rotation-difference-sensitive differential limiting device, differential limiting torque is less likely to occur during steady running, especially in the high-speed range, so it is not very effective in improving running stability by suppressing overshoot of yaw rate. Can not be expected.

The present invention has been made in consideration of such a problem, and by using an active control type differential limiting device, the differential limiting torque is controlled so that the vehicle obtains a desired yaw rate. The purpose is to improve the running stability of the vehicle.

[0005]

According to the first aspect of the invention, in a vehicle having an active control type differential limiting device a as shown in FIG. 7, a means b for detecting a vehicle speed and a means for detecting a steering angle of the vehicle. c, a means d for calculating an actual yaw rate based on these detection signals, a means e for similarly calculating a target yaw rate, and a differential limiting torque controlled so that the actual yaw rate matches the target yaw rate from these calculated values. Means f for doing so.

According to the second aspect of the invention, in a rear-wheel drive vehicle equipped with an active control type differential limiting device g as shown in FIG. 8, a means h for detecting the left and right wheel speeds of the front wheels and an average value of these detected speeds. As a vehicle speed, a means j for detecting the steering angle of the vehicle, a means k for calculating an actual yaw rate based on these vehicle speed and steering angle, and a means m for similarly calculating a target yaw rate. Means n is provided for controlling the differential limiting torque so that the actual yaw rate matches the target yaw rate from the calculated value.

[0007]

According to the first aspect of the invention, the actual yaw rate and the target yaw rate are calculated based on the vehicle speed detection signal and the steering angle detection signal, and the actual yaw rate and the target yaw rate are differentiated from these calculated values. The limiting torque is controlled. Therefore, the differential yaw rate that makes the actual yaw rate follow the target yaw rate is applied, and the yaw moment of the vehicle is controlled.Therefore, the yaw rate does not overshoot, and the driving stability is suppressed by suppressing the tail swing when changing lanes. A great effect can be obtained in improving the sex.

According to the second aspect of the invention, the vehicle speed is set to the average value of the left and right wheel rotations of the front wheels which are unlikely to cause slippage in the non-driving wheels. Therefore, the same control as in the first aspect is performed. The yaw moment of the vehicle can be controlled accurately.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of application to a rear-wheel drive vehicle. A differential 1 having an active control type differential limiting device 2, a control unit 3 for controlling the differential limiting torque, and front wheels ( The control unit 3 includes rotation sensors 4 and 5 that detect the left and right wheel speeds of non-driving wheels and a steering angle sensor 6 that detects the steering angle of the vehicle, and the control unit 3 detects the detection signals of the rotation sensors 4 and 5 and the steering angle sensor 6. On the basis of the detection signal of 1, the differential limiting torque is calculated as described later, and the coil current corresponding to this is output to the differential 1.

The differential limiting device 2 of the differential 1 is
As shown in FIG. 2, the main clutch 7 and the pilot clutch 8
And the electromagnet 9 and the like. By passing a coil current through the electromagnet 9, the attraction force of the electromagnet 9 acts on the pilot clutch 8 to generate pilot torque (friction torque).
The pilot torque is converted to thrust force by the cam 10,
Since the main clutch 7 is pressed, differential limiting torque proportional to the coil current is generated. 11 is a pinion gear,
Reference numeral 12 indicates a side gear.

The control contents of the control unit 3 will be described with reference to the flowchart of FIG. 3, which is repeatedly executed at a predetermined control cycle. In addition, the formula 1 in the flow in FIG.
~ The meanings of the symbols used in Formula 7 are shown in the table. First, the detection signal (wheel speed) of each rotation sensor 4 and 5 is read, and the average value of these is calculated as the vehicle speed (1.01, 1.0
2). Further, the detection signal (steering angle) of the steering angle sensor 6 is read (1.03). Then, the target yaw rate and the actual yaw rate are calculated based on these vehicle speed and steering angle (1.0
4, 1.05).

The calculation process of the target yaw rate is repeated in the order of the equations 1 to 4, and the stability factor is calculated by the equation 1. The yaw rate gain is obtained by the equation 2, and the yaw angular acceleration is calculated by the equation 3. As the yaw rate, zero is given as an initial value, and when the calculation of the yaw angular acceleration is completed, this is integrated by Equation 4 to obtain the yaw rate used for the next calculation.

The actual yaw rate is expressed by Equation 5 which represents a lateral movement.
And the simultaneous differential equation of Equation 6 representing the yawing motion are solved. This calculation process is also executed in the control cycle, and the actual yaw rate that changes from moment to moment is calculated.

Based on the target yaw rate and the actual yaw rate, the differential limiting torque is calculated by the equation 7, and the coil current corresponding to the torque value is output to the electromagnet 9 of the differential limiting device 2 (1.06). . FIG. 4 shows the control characteristics of the coil current.

Therefore, since the differential limiting torque that causes the actual yaw rate to follow the actual yaw rate is applied to control the yaw moment of the vehicle, the overshoot of the yaw rate is eliminated as shown by the dotted line in FIG. A great effect is obtained in improving running stability such as suppressing tail swings.

When applied to a commercial vehicle in which the load varies greatly, a load sensor for detecting the load of the vehicle is added to control the differential limiting torque based on the vehicle speed, the steering angle and the load. May be.

[0017]

According to the first aspect of the invention, in a vehicle equipped with an active control type differential limiting device, a means for detecting a vehicle speed, a means for detecting a steering angle of the vehicle, and a detection signal based on these means are used. Since the means for calculating the actual yaw rate, the means for calculating the target yaw rate, and the means for controlling the differential limiting torque so as to match the actual yaw rate with the target yaw rate from these calculated values are provided, follow the target yaw rate. Since the yaw rate overshoot is eliminated by applying the differential limiting torque as described above, it is possible to obtain a great effect on the improvement of the running stability such as the suppression of the tail swing when changing lanes.

According to the second aspect of the invention, in a rear-wheel drive vehicle equipped with an active control type differential limiting device, means for detecting the wheel speeds of the left and right front wheels and an average value of these detected speeds is calculated as the vehicle speed. Means, a means for detecting a steering angle of the vehicle, a means for calculating an actual yaw rate based on these vehicle speed and steering angle, a means for similarly calculating a target yaw rate, and a target yaw rate from these calculated values as a target yaw rate. Since the means for controlling the differential limiting torque is provided so as to match, the average value of these values is used as the vehicle speed from the wheel rotation of the left and right wheels of the front wheels that are unlikely to cause slippage in the non-driving wheels.
By performing the same control as in the first aspect of the invention, the yaw rate of the vehicle can be controlled appropriately.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an entire apparatus.

FIG. 2 is a sectional view of a differential limiting device.

FIG. 3 is a flowchart illustrating control contents of a control unit.

FIG. 4 is a list showing meanings of symbols for explaining control contents.

FIG. 5 is a control characteristic diagram of a coil current.

FIG. 6 is an explanatory diagram of a steering angle and a yaw rate.

FIG. 7 is a configuration diagram showing a first invention.

FIG. 8 is a configuration diagram showing a second invention.

[Explanation of symbols]

 1 Differential 2 Differential limiting device 3 Control unit 4,5 Rotation sensor 6 Rudder angle sensor

Claims (2)

[Claims] 1. In a vehicle including an active control type differential limiting device, means for detecting a vehicle speed, means for detecting a steering angle of the vehicle, and means for calculating an actual yaw rate based on these detection signals, Similarly, the differential limiting control device is provided with means for calculating the target yaw rate and means for controlling the differential limiting torque so that the actual yaw rate matches the target yaw rate from these calculated values. 2. A rear wheel drive vehicle including an active control type differential limiting device, means for detecting wheel speeds of left and right front wheels, means for calculating an average value of these detected speeds as a vehicle speed, and steering of the vehicle. Means for detecting the angle, means for calculating the actual yaw rate based on these vehicle speed and steering angle, means for similarly calculating the target yaw rate, and differential values for matching the actual yaw rate with the target yaw rate from these calculated values. A differential limiting control device comprising means for controlling a limiting torque.